Phase-Matched Second-Harmonic Generation from Metasurfaces Inside Multipass CellsMadona Mekhael, Timo Stolt, Anna Vesala, Heikki Rekola, Tommi K. Hakala, Robert Fickler and Mikko J. HuttunenEPJ Web Conf., 309 (2024) 08006DOI: https://doi.org/10.1051/epjconf/202430908006